Radiation therapy is increasingly used for treatment of such diseases as cancer in which tissue irradiation is used to selectively destroy certain body tissues. Radiation therapy now typically involves the use of X-ray beam generators such as linear accelerators, since naturally occurring radioactive substances suitable for this purpose more often relied on in earlier years have been replaced by more effective linear accelerators.
Linear accelerators generate electromagnetic radiation as an incidental byproduct of operation of the various electrical components incorporated therein. Electromagnetic fields have been known to create problems in the functioning of heart pacemakers, so that some risk is presented to patients having implanted pacemakers when undergoing radiation treatment with the use of linear accelerators. Shielded pacemakers have been designed for protection against malfunction during MRI imaging, but this approach increases the cost of the pacemaker and does not solve the problem for existing pacemakers. See U.S. Pat. No. 5,217,010 issued on Jun. 8, 1993 for an "EKG Amplifier and Cardiac Pacemaker for Use During Magnetic Resonance Imaging."
Shielding garments having interwoven metallic strands have also been devised for protection during MRI examinations, but this approach is not effective for protection during radiation therapy since the presence of metallic elements close to the patient's skin can cause injury due to beam scattering caused by the beam reflecting from the metal. See U.S. Pat. No. 5,103,504 issued on Apr. 14, 1992 for a "Textile Fabric Shielding Electromagnetic Radiation and Clothing Made Thereof."
While so-called Faraday cages have been used to isolate hyperthermia equipment and protect patients, heretofore no protection has been afforded radiation therapy patients.
Thus, a satisfactory solution to this problem has not heretofore been provided.
The object of the present invention is to provide reliable protection for patients having an implanted heart pacemaker while undergoing radiation therapy, protecting against the particular effects of electromagnetic radiation on pacemaker functioning, which is effective for existing implanted pacemakers, and which shielding does not itself cause injury to the patient's skin during radiation therapy.